U N ITED STATES ENVIRONMENTAL PROTECTION AGENCY

The Honorable C.L. "Butch" Otter Office ofthe Governor P.O. Box 83720 Boise, Idaho 83720 Dear Governor Otter: REGION 10 1200 S ixth Aven ue , S uite 900 Seattle, WA 98101
-3140 

## AUG 19 2014 OFFICE OF THE REGIONAL ADMIN ISTRATOR

Thank you for your recommendation dated December 6, 2013 ofair quality designations for the 2012 revised primary annual fine particle (PM2
.s) National Ambient Air Quality Standard (NAAQS) throughout Idaho. I appreciate the information Idaho shared with the U
.S. Environmental Protection Agency as we move forward to improve PM2
.s air quality

. This letter is to notify you ofthe EPA ' s preliminary response to Idaho ' s recommendation and to inform you ofour approach for completing the initial area designations for the 2012 revised primary annual PM2. s standard

. On December 14, 2012, the EPA promulgated a revised primary annual PM2.s NAAQS (78 FR 3086, January 15, 2013). In that action, the EPA revised the primary annual PM2.s standard, strengthening it from 15
.0 micrograms per cubic meter (Jlg/m3 ) to 12
.0 ).!g/ m3 ; retained the existing 24-hour PM2.s standard at 35 Jlg/m3 ; retained the existing 24-hour PM 10 (coarse particle) standard at 150 J..lg/m3 ; and retained the current suite ofsecondary PM standards

. The EPA revised the primary annual PM2.s standard based on an integrated assessment ofan extensive body ofnew scientific evidence, which substantially strengthens our body ofknowledge regarding PM2
.s-related health effects. The revised primary annual PM2.s standard will provide increased protection for children, older adults, persons with pre-existing heart and lung disease, and other at-risk populations against an array ofPM2. s-related adverse health effects, including premature mortality, increased hospital admissions and emergency department visits, and development and exacerbation ofchronic respiratory disease

. History shows us that better health and cleaner air go hand-in-hand with economic growth. Working closely with the states and tribes , the EPA is implementing the standards using a commonsense approach that improves air quality and minimizes the burden on state, local, and tribal governments. As part of this routine process , the EPA is working with the states and tribes to identify areas in the country that meet the standards and those that need to take steps to reduce PM2
.s air pollution. Within one year of promulgating a new or revised air quality standard, the Clean Air Act requires the Governor ofeach state to submit to the EPA a list ofall areas in the sta t e, with a designation recommendation for each area. As a first step in implementing the 2012 annual PM2.s standard, Governors were to submit their designation recommendations, including appropriate area boundaries, by December 13 , 2013
. As required by the Clean Air Act, the EPA then promulgates designations for all areas across the country. The EPA designates an area as "nonattainment" ifit is violating the 2012 annual PM2.s NAAQS or ifit is contributing to a violation ofthe NAAQS in a nearby area. Consistent with designations for previous PM2.s standards, the EPA intends to use a designation category of " unclassifiable /attainment" for areas that are monitoring attainment or do not have monitors , but for which the EPA has reason tobelieve are likely attainment and are not contributing to nearby violations
. Additionally, the EPA intends to designate as ' 'unclassifiable" those areas where the EPA cannot determine based on available infonnation whether the area is meeting the NAAQS or where EPA has not determined that the area contributes to a nearby violation. At this time, the EPA is proceeding with intended initial area designations using quality-assured, certified air quality monitoring data from 2011 to 2013. Based on Idaho's 2013 annual 

### PMz
.s designation recommendation letter, extensive collaborative discussions with the Idaho Department ofEnvironmental Quality (IDEQ), and consideration ofother relevant technical information, including 2011

- 2013 air quality data and 2014 technical analyses, the EPA intends to designate a partial area of Shoshone County (limited to areas surrounding the towns of Pinehurst, Smelterville, and Kellogg) as nonattainment. A Technical Support Document, which provides a detailed analysis to support this preliminary decision is enclosed and is also available on the EPA's website at http: //www.epa.gov/ pmdesignations/2012standards/state.htm. The EPA will continue to work closely with the IDEQ regarding the appropriate boundary for the area in Idaho. Ifthe State has additional information for the EPA to consider, please submit it to us by October 29, 2014. The EPA intends to designate all other areas ofthe state as unclassifiable/attainment. The EPA will make its preliminary designation decisions and supporting documentation available to the general public for review and comment. We will be announcing a 30-day public comment period shortly in the 

### Federal Register. After considering the additional information we receive, the EPA plans to promulgate final annual 

### PMz.s designations in December of2014. The EPA is committed to working with the states and tribes to share the responsibility ofreducing 

### PMz.s air pollution. Current and upcoming federal standards and safeguards- including pollution reduction rules for power plants, vehicles, and fuels

- will ensure steady progress to reduce PMz.s-forming pollution and will protect public health in communities across the country. We look forward to a continued dialogue with you and your staff as we work together to implement the 2012 annual 

### PM z.s standard
. Should you have any questions , please do not hesitate to contact me, or have your staff contact Justin Spenillo ofmy staffat spenillo.justin @ epa.gov .

Regional Administrator

cc: Curt Fransen, Director Idaho Department ofEnvironmental Quality Tiffany Floyd, Administrator Idaho Department ofEnvironmental Quality Janet G. McCabe, Acting Assistant Administrator Office ofAir and Radiation Stephen D. Page, Director Office ofAir Quality Planning and Standards